Method of procedure for sensitizing kinofilms for positive copies by means of solutions of bichromate



F atented Dec. 1,1925.

UNITED .ST-ATES PATENT OFFICE;

ALFRED WEINGARTEN, OF BERLIN, GERMANY.

METHOD OF PROCEDURE FOR SENSITIZING KINOFILMS FOR POSITIVE COPIES BY MEANS OF SOLUTIONS OF BIGHROMATE.

No Drawing.

To all whom it may concern: Be it known that I, ALFRED WEINGARTEN, a citizen of Poland, residing at Berlin, Germany, have invented new. and useful im -provements in methods of procedurefor sensitizing kinofilms for positive copies by means of solutions of bichromate, of which the following is a specification.

This invention relates to a method of procedure for sensitizing kinofilms for positive copies by means of solutions of bichromate. In comparison with the present state of technics th1sv rocedure has the advantage, that accor ing to the new mode of procedure the duration of exposing to the light can be considerably reduced, and the durability ofjthe sensitized film d'f gelatine is raised in comparison with the known methods of sensitizing by means of bichromates, as applicant has observed.

Essentially the-procedure consists in sensitizing by ans of a solution of bichromate the first celluloidlayer coated with a layer of elatine. Accordi to the invention th1s layer is bathed in a solution of potassium bichromate, potassium ferro Application filed January 15 1925. serial No. 1,959.

cyanide and potassium bromide (for in.- stancef0r 1 liter of solution parts of potassium bichromate, 5 parts potassium ferro-cyanide and 5 .parts potassium bro- 80 mide). But the solutlon may be added to the colloid, before the latter is brought up to the celluloid band. Thereupon the sensitized layer is exposed tothe light, washed by means of cold water and, then, developed in warm water, eventually upon previous colouring. With certain colloids the development can be obtained in a known manner without warm water; i. e. in a cold way. The not exposed gelatine swells, then, in such a measure, that the image becomes visible in the wet state.

What I claim is A method of sensitizing kinofilms for positive copies, consisting in bathing the colloid in a solution of potassium bichr'omate, potassium ferro-cyanide and potassium bromide.

Intestimony -whereof I have signed my name to this-specification.

ALFRED WEINGARTEN. 

